Mechanical file



R. BARNES MECHANICAL FILE Original Filed Dec. 4, 1936 2 Sheets-Sheet lUm max R. BARNES MECHANICAL FILE Original Filed Dec. 4, 1936 2Sheets-Sheet 2 IN VEN TOR. ,Vlf'was.

Patented Dec. 10, 1940 PATENT OFFICE MECHANICALFILE Robert Barnes, SanFrancisco, Calif, assignor to Guy E. Russell, San Francisco, Calif.

Application December 4, 1936, Serial No. 114,236 Renewed February 26,1940 4 Claims.

The present invention relates to improvements in a mechanical file andhas reference generally to abrading, smoothing and polishing tools.

Where considerable filing and polishing is to be done, as in thepreparation of the surfaces of an automobile prior to the application ofsurface coatings, it is customary, at thepresent time, to provide asuitable, hand-operated carrier, to the bottom face of which the file isattached and which is manipulated by pushing the same back and forthover the surface to be treated.

In the present invention it is proposed to substitute power-operated forhand-operated means and to provide power-operated means in thecarrierfor rapidly reciprocating the file so that the operator isrelieved of the burdenand may devote his entire attention to the holdingand guiding of the carrier. This power-operation has the furtheradvantage of allowing of much quicker reciprocation than is possiblewhere manual power is relied on.

It is furtherproposed to provide means in connection with this inventionwhereby the speed of reciprocation may be adjusted.

5 It is further proposed to provide means for adjusting the length ofstroke of the reciprocating file.

It is further proposed to ,use compressed air as the driving means formy mechanical file and to provide control means positioned forconvenient operation by the hand of the operator holding the tool.

It is still further proposed to provide a novel lubricating means forthe moving parts of my inventi'on whereby a lubricant is entrained inthe compressed air used as the driving means.

It is further proposed to provide means Whereby the air exhausted fromthe device may be used to clean and cool the surface on which the fileworks.

And finally, it is proposed to combine all the features outlined into acompact structure, which is comparatively simple in construction,durable in operation and easy to handle.

Further objects and advantages of my invention will appear as thespecification proceeds.

The preferred form of my invention is illustrated in the accompanyingdrawings, in which:

Figure 1 shows a side view of my mechanical file,

Figure 2 a top plan view thereof,

Figure 3 a central, vertical, longitudinal section through the device,

Figure 4 a transverse vertical section taken 55 along line 4-4 of Figure3,

Figures 5 and 6 schematic detail views explaining the valve operation.

While I have shown only the preferred form of my invention I wish tohave it understood that various changes or modifications may be made 5within the scope of the claims hereto attached Without departing fromthe spirit of the invention. More particularly I Wish to have itunderstood that while I described the tool as a mechanical file it maybe readily used for any 10 smoothing, polishing and sanding operation bysubstituting any desired abrasive surface for that shown in thedrawings.

Referring to the drawings in detail, my mev chanical file I comprises anelongated housing 2 15 comparable in general outlines to theconventional Wooden plane and having a handle 3 at the rear end and agripping member 4 attached over the front end, so that it may beconveniently manipulated by grasping the handle with one 20 handv andthe gripping member with the other hand.

The housing is cored from opposite ends to provide two longitudinalcylinders I4 separated by a central partition I5 which latter is cored'25 from one side to provide a valve chamber 16 (see Figure 4) betweenthe two cylinders. Each of the cylinders has a piston l'l reciprocabletherein and the two pistons are interconnected, by means 7 V of a slidel8 riding on the underface of the hous- 0 ing, the slide being securedto the outer ends of the pistons as at l9 and the cylinder walls havingslots 20 to permit the connections-2| between the pistons and the slideto travel therein.

The pistons are reciprocated by means of com- 35 pressed air in thefollowing manner: A nipple 22 arranged above the handle 3' is connectedto a source of supply and leads the compressed air, through a tube 23,to aradial port 24 in the plug 25 used for closing the outer end ofv oneof the i0 cylinders, and the radial port connects with an axial port 26leading to a small chamber 21 formed upon the outer end of the plug bymeans of a diaphragm 28.

A stud 29 projecting from the outer face of 45 the diaphragm isconnected to one end of a curvedlever 3B pivoted to the handle as at 3|and pressed upon by the spring 32 which tends to close the port 26. Thefree end of the lever 30 is arranged in substantially parallel relationto the gripping portion of the handle 3 and so as to slightly projecttherefrom, which permits the operator to open the port 26 by a slightpressure of his fingers upon the lever. When the port 26 isopened inthis manner, compressed air enters the chamber 2! and passes throughconduits 33, 34, and 35 into the valve chamber IS in the centralpartition.

The valve chamber I6 is closed by means of a plug 36 and the valveitself comprises a disc 31 bearing upon the inner end of the valvechamber and having a shaft 38 projecting through the plug 36, while aspring 39 urges the valve upon its seat. The inner ends of the twocylinders 4 are connected to the inner wall of the valve chamber bymeans of two ports 40 and 4| arranged in spaced relation to one anotherand the valve disc 31 is formed with a port 42 which is made to registerwith one or the other of the two ports 40 and 4| as the disc is made tomove from one position to another. The means for effecting this valvemovement will be discussedlater.

The valve disc 31 is also formed with two radial grooves 43 and 44, onopposite sides of the port 42 and these grooves are positioned so thatwhen the port 42 registers with one of the ports 40, 4|, the outer endof one of the grooves communicates with the other port and connects thesame to the exhaust passage 45 in the housing so that when one of thecylinders receives the pressure medium, the other one exhausts and viceversa.

The exhaust conduit is controlled by a threaded plug 45 which isoperated by means of a disc 4'! engaging the squared end of the plug andheld to the housing by the holder 48 screwed to the housing as at 49.The holder has an aperture 50 through which the disc appears and thelatter is suitably graduated for comparison with a mark 5| on the holderso that the disc may be set to any desired position.

It is apparent that the port area of the exhaust determines the speed atwhich compressed air may be passed through the device and that thereforethe piston speed may be controlled by the proper setting of the disc 41,which latter is preferably marked Speed control (see Figure 2). As thesize of the exhaust port is decreased, the length of time required tocom- 45 pletely exhaust the cylinders is increased correspondingly.

The exhaust conduit is continued beyond the plug to pass downward as at52 (see Figure 4), and to discharge toward the surface worked on by thetool for cleaning and cooling the latter surface.

The valve disc 31 is operated as follows:

The outer end of the shaft 38 has a crank arm 53 which is connected,through a spring 54, with the long arm of a lever 55 pivoted as at 56 insuch a manner that the two connected ends swing on opposite curves sothat, when the crank arm occupies one operative position and the leverarm is swung in the opposite direction the spring causes the crank armto follow with a snap action, since the spring is made to expand andcontract during the movement. Suitable stops 51 are provided to limitthe valve movement.

The lever 55 is actuated, that is, swung in one,

direction or the other at the end of each piston movement, by means oftwo shoes 58 and 59 arranged in an elongated slot 6|] in the slide l8 onopposite sides of the lower arm 6| of the lever 55. The two shoes aremounted on opposite threads of a rod 6| supported in the slide and heldagainst endwise motion by a screw 62 riding in a registering annulargroove in the rod.

The rod may be turned by any suitable tool engaging the squared end 63thereof and the spacing between the shoes may thus be adjusted.

One of the shoes strikes the lever 55 at the end of each piston movementfor effecting a reversal of the valve 3'! and it is apparent that thespacing between the shoes controls the length of the piston stroke 50that the latter may be changed as desired by adjusting the spacingbetween the shoes.

The main slot of the slide, in which the two shoes are adapted to move,is extended laterally to the edge of the slide as shown at 69 and atleast one of the shoes has a thin lateral extension 10 projectingthrough the slot so as to be visible from the outside for reading with ascale placed on the outside of the housing adjacent the slot so that thespacing between the shoes may be ascertained from the outside.

The pistons I! have particular lubricating feature insofar as they areformed with pockets 12 facing the compression chambers, each pocketbeing filled with felt 13 or other absorbent material, and the feltbeing saturated witha lubricant. The open end of the pocket 'is closedby means of a perforated cap 14, which allows a portion of thecompressed air to enter the pocket and to entrain a slight amount of thelubricant, whereby all the working faces contacted by the air arecontinuously lubricated. New lubricant may be admitted to each pistonfrom the outer end, as shown at T5.

The front end of the front cylinder may be suitably closed by aremovable front wall I6 and the valve operating mechanism may be coveredby a plate 11.

The slide I8 is formed with suitable mounting means for the file l3which may comprise two spaced, undercut elements 54 and 35 adapted toreceive the file between the same, the file being formed with beveledend edges 66 fitting into the undercuts. The element is preferably madeadjustable by being dovetailed into the slide as at 6! (see Figure 3),and may be tightened upon the file by the screw 68.

The operation of my device will be readily understood from the foregoingdescription and particularly from the diagrammatic views of Figures 5and 6. Figure 5 shows the valve mechanism substantially in the positionof Figure 3, in which the shoe 59 has struck the lower end of the lever55 and has thereby effected a change in the valve position so thatcompressed air passes through the conduits 34 and 35 into the valvechamber I6 and thence through port 42 in the disc 31 and the port 4| inthe partition and into the right-hand cylinder of Figure .3, while theair from the left-hand cylinder is exhausted through the port 40, thegroove 43 in the valve disc 31 and the exhaust port 45.

The two pistons will now move to the right (see Figure 3) until thesecond shoe 58 strikes the lower end of the lever and reverses the partsas shown in Figure 6. The spring 54 has been omitted from thediagrammatic showing for the purpose of clarity, but it is apparent thatas the upper end of thelever is swung from right to left, the crank armfollows the movement with a snap action due to the expansion andcontraction of the spring.

In the new position the conduits 34, 35 connect with the valve chamber,as before, but the compressed air is admitted into the left-handcylinder through the valve port 42 in the disc 31 and the partition port40, while the right hand cylinder is connected to the exhaust throughthe partition port 4|, the valve groove 44 and the port 45,,

whereby a reversal of the piston movement is effected.

The admission of the air is controlled by the hand lever 30. The pistonstroke may be adjusted by positioning the shoes 58 and 59 and the pistonspeed may be controlled by adjustment of the plug 46 in the exhaustpassage.

I claim:

1. In a tool of the character described, a housing having a pair ofalined cylinders therein and a partition interposed between thecylinders, a pair of pistons spaced apart and reciprocable in thecylinders, means for introducing pressure means into the cylindersbetween the partition and the inner faces of the pistons forreciprocating the latter, a valve control for the pressure means mountedin the partition between the pistons, the valve control having meansassociated therewith for exhausting one cylinder when pressure means isbeing introduced into the other cylinder, a tool holder having means forsecuring a tool thereto and being reciprocable upon the outside of thehousing in parallel relation to the piston movement, the housing havingslots therein, and means slidable in the slots for connecting thepistons to the tool holder for transmitting reciprocating motion to thelatter.

2. In a tool of the character described, a housing having a pair ofalined cylinders therein and a partition interposed between thecylinders, a pair of pistons spaced apart and reciprocable in thecylinders, means for introducing pressure means into the cylindersbetween the partition and the inner faces of the pistons forreciprocating the latter, a valve control for the pressure means mountedin the partition between the pistons, the valve control having meansassociated therewith for exhausting one cylinder when pressure means isbeing introduced into the other cylinder, a tool holder having means forsecuring a tool thereto and being reciprocable upon the outside of thehousing in parallel relation to the piston movement, the housing havingslots therein, and means slidable in the slots for connecting thepistons to the tool holder for transmitting reciprocating motion to thelatter, the sliding tool holder having means thereon for operating thevalve control.

3. In a tool of the character described, a housing having a pair ofalined cylinders therein, a

' pair of pistons reciprocable in the cylinders,

means for introducing pressure means into the cylinders active on theinner faces of the pistons for reciprocating the latter, a valve controlfor the pressure means mounted between the pistons, a memberreciprocable upon the outside of the housing in parallel relation to thepiston movement, the housing having slots therein, and means slidable inthe slots for connecting the outer ends of the pistons to the saidmember for transmitting reciprocating motion to the latter, the slidingmeans having means thereon for operating the valve control and thelatter means being adjustable for adjusting the stroke of the piston.

4. In a tool of the character described, a manipulating means for arotary valve comprising a crank arm operating the valve, a lever mountedin confronting relation to the arm and eccentrically relative thereto,means for engaging one end of the lever for alternately thrusting thesame in opposite directions and a spring connection between the end ofthe arm and the other end of the lever, the latter two ends being madeto swing on opposite curves.

ROBERT BARNES.

